The monocyte-macrophage participates in many T- and B-lymphocyte functions and in the host responses to many infectious organisms. To determine whether abnormal monocyte function occurs in the acquired immune deficiency syndrome (AIDS), a disease characterized by T- and B-cell defects and an unusually high incidence of certain protozoan, viral and fungal infections, we are investigating the expression of various functions by monocytes from patients with AIDS. Specifically, we are characterizing the ability of monocytes to exhibit chemotaxis, to express cytotoxic activity, to produce mediators such as prostaglandin E2 and interleukin 1, and to generate microbicidal oxygen metabolites. Also, we are determining whether these monocyte activities can be augmented by immunomodulatory therapy. In addition, we are investigating the ability of cytomegalovirus (CMV) to infect monocytes and the effect of CMV infection on monocyte function. Finally, we will relate the findings from these studies to our clinical investigations into the microbiological manifestation of gastrointestinal disease in AIDS. These studies will provide insight into the participation of monocytes-macrophages in the immunosuppression in AIDS.